The present disclosure relates in general to the field of quantum processing hardware apparatuses comprising superconducting qubit driven by radio frequency signals and, in particular, to techniques for thermalizing radio frequency signals in such apparatuses.
Recent advances in quantum computing are making such a technology ever more relevant to industrial applications. Quantum computing makes direct use of quantum-mechanical phenomena, such as superposition and entanglement to perform operations on entangled quantum bits (qubits), i.e., information stored in quantum states. Superconducting circuits are relatively easy to manufacture with current technologies and are thus candidates to further scale quantum information technologies. Today, it can be envisioned that in the near term a small quantum computer, based on a couple of hundreds of superconducting qubits with error mitigation or limited error correction, will be able to simulate quantum systems intractable to conventional computers.
Quantum computing devices are known, which are based on superconducting qubits of the transmon type. Such qubits are controlled by radio frequency (RF) technology. Such qubits need be operated at a temperature of a few mK only. RF signals are fed into the cryostat with coax cables using attenuators placed on intermediate temperature platforms to thermalize the signals for each of the upward and downward path. The attenuators are cooled to the temperatures of their respective platforms. In total, approximately 60 to 90 dB of attenuation is typically ensured between the signal generator and the qubits, thanks to such attenuators.